Drill bit



8 26, .1952 v c. v. TILDEN Re. 23,539

. DRILL BIT Original Filed Sept. 20, 1947 11 10 v 12 I V r I INVENTOR.

Reissued Aug. 26, 1952 UNIT E D S TAT ES; PATE- NT F F ICE DRILL BITCarl'V'. Tilden, Altadena, Calif;

originalnNo; 2,506,474; dated Mayz, 1950, Serial No. 775,186,- September20,1947.

Application for reissue- Aprilc30, 1951, SeriaLNo..223,69.3.

12' Claims.--'

Matter 'enclosedin-"heavy, brackets Iappearsin-theo1-iginal:.patent...but.forms no. partot this! reissuespecification; matter printed in .italics 'indicates vthe additionsmadeby reissue;

1; My invention relatesgenerally to' rotary bits: and particularly tobits for drilling holes in hard.

granular, structures such, as brick, concrete, and

other masonry formedjof' aggregate and binding. material.

More particularly my, invention has reference todrillbits of the type.having a solidj body with a disc-shaped, head of concentric externalcircumfere'nce fixed on one endofthe body concentrically to theaxis. ofrotation thereof ;'v teeth set radially in the face of the head.andperpendicular.

to the axis of rotation; and withor without a. screw thread or anger ontheexterior. of the body for removing material cuttings from. the-holebeing drilled.

Bits of this character as heretofore proposed have a low drillingefiiciency. for thereason that as drilling proceeds in ahole-the drill'is not.re-,

11eved..of the material cuttings with sufiicient rapidityto preventaccumulation thereof inthe hole. As aconsequence, the accumulated. cut.-tings offer considerable. resistance to rotation of. theqdrill; andhence, impede. its drilling action, thus requiring, more time and powerthan .isactually necessary to drilla hole of any. given depth.

Accordingly, it is a purpose of. my invention to provide a drill bit ofthis typer'which is char.- acterized functionally by it's. ability whendrilling. a hole in masonry tocontinuouslyand completely, remove thematerial cut..from-th'e cuttinglfacev of the bit, as well asf'rom thehole, in am-annerto continuously'relieve the bit and hole of the-cutmaterial, andto thus accelerate the.drillir'lg.ace tion ofthe' bit tothe extent of greatly reducing the power and time requiredto drill, a.hole. of any given depth.

It'is'. also a purpose ofmy invention tovprovid'e a drill bitwhich'embodies dual means for conveying the material from the hole cutby the bit, oneof these means. being exterior and the other interior. tothebody of the bit, with the two means joining at a: point spaced fromthe cutting face ina mannerin which they may further reduce Fig; 2-is anend view of the dri-ll bit', showing the cutting face-thereof.

Fig. 3 is a longitudinal sectional view-*on the line[s ]"33 of Fig.2-illustrativeof'the drilling actionof the drill bit irra masonrystructure:

Fig. 4" is across-sectional view taken-onthe- 1ineEs] -4'4'of*Fig. 1-.

Fig. 5-is an elevational-view, similar-to Fig. 1;

but withthe -drill bit rotated ninetydegrees toillustrate the slotcommunicating betw-eenthe=e-xterior of the bit and the-interior-thereofvHaving specific reference to. the drawings, this embodiment of myinvention-comprises an elongatedbodyl0= of circular cross-section havinganaxial [bore H.- trailing or proximal endof the body l0, by;- a shank"l2 securedthereto, sothatthe bore-forms apassage, pocket or'recess; Theleading'or distal end of the-body 'l0 is enlarged-toform an annular'head' l3, and the face --l4 -thereofhas teeth I5 set: therein. Theteeth l5; of which there-may;

befour or any othersuitable number, arewpref erably made of--cementedcarbide,- and are dispos ed-in-acirclearound the borel 1', so that theircutting edges, which are the leading edges upow rotation, areapproximatelyradial tothe head I 3;

while their outer ends project outwardly from=the=- periphery-ofthehead, and their inner ends project-into the bore- I I, asbest-illustrated -'in- Fig-,- 23' The individual teeth-are shaped attheir cutting ends by havingtheir-corners cut 017 cum-angle toprovide-in each instance-cutting edge po'rtions which lie respectivelyin a-plane-normal' tO-th a longitudinal axis-ofthe body and'implanes'which diverge from-anintersecting line located forward ofthe-drill end. This shaped) the-ends o'fthe;

teeth is clearly shown-inthe drawing and causes a circular channelhaving outwardly lemming -side wallsto be formedas-thedrillend-rotates-in-con--- tactwith the material being-drilled;The sloping sidewalls ofthe =holeper-,for-md drillcentering function inan obvioustmanner.

A'spiral threadl 1 isprovidedon theoutersur faceof the bodyl0, forminganauger for carrying away cuttingsin the form of granules-of 'the' 1material beingdrilled Thethread l l is preferably of squarecross-section, in the-manner of a:

SellersSquare thread; and extends-froma point near the -head l 3 to.Ith'e proximal end of the body ID.- Between the distalend'of the threadH and the head l3; the body;Hi-isreduceddn'size'to its" diameter at thebottom of the grooves Haof-the:-- thread,- so i as to leave-an annulargroove-l 8 adjacent tothe head; The periphery-ofthelheadi I3. isflattened, as-at l-9- (see- Fig=.- 5), to' -fornr shallow channels orclearances in-advance:- off 3 each of the teeth I5, leading from theface I4 to the annular groove I8 when the bit is inserted in a hole, andthrough which finely comminuted particles may pass between the outerends of theteeth I to the groove [8, and thence to the auger thread H.

A slot 2| is formed in and extends longitudinally of the body In from apoint where it intersects the annular groove IE to a point a few threadsdistant from the proximal end of the body 10. The slot 2| communicateswith the bore II and interrupts the threads of the auger thread H whereit intersects them, providing a passage for granular material and chipsfrom the bore I I to the auger thread along the major part-of thelatter. A shallow longitudinal groove 22 extends from and incontinuation of the slot 2|, to the proximal end of the body I0,providing a passage supplementary to the slot or to that passageprovided by the auger thread I! by which the drilledout material mayreach the zone around the shank I2.

In the operation of drilling a hole in masonry structures, the teeth I 5will cut an annular channel therein, tending to form a central core inthe leading end of the bore I I, but because the inner ends of the teethproject into the bore II they operate to grind up the core as it isformed. Because the outer ends of the teeth I 5 project slightly beyondthe periphery of, the head I3, the hole will be slightly oversize andwill not bind upon the bit as the bit progresses inwardly.

Finely comminuted materials, cut from the face of the hole by the teethI5, will move through the clearances I9 to the annular groove I8 andthence to the auger thread groove Hat by which it is removed from thehole. [Those] Some of the particles of the material dislodged at theface of the hole will enter the bore II through the open end thereofbetween the inner ends of the teeth I5 to be subjected to the grindingaction of the teeth in the disintegration of the core as it is formedIf, and thus the]. The core is broken up as rapidly as it is formed [tooffer] and oflers no impediment to the free flow of the material in thebore.

The slot 2| permits the material to be thrown by centrifugal forceoutwardly of the side of the bit at that part of the slot projectingfrom the hole, either when drilling horizontally or downward. Whendrilling upward the exposed part of the slot allows the material togravitate from the bit aided, of course, by centrifugal force.

At that part of the bit within the hole, the slot 2| permits theimmediate discharge to the auger thread ll of a part of the materialsuited in size to passage along the thread. If too large to enter theauger thread they are immediately ground against the wall of the holeand battered by the sides of the slot until suitably comminuted. Thesharp inner and outer edges of the slot 2| assist materially inrendering this battering action effective. The Sellers Square thread I1is also of assistance in this respect, presenting fiat radial surfacesand substantially rectangular corners at its intersections with the slot2|, well adapted to batter and grind material passing through theintersections without injury to the thread.

Material entering the auger thread I1 is rapidly conveyed to the face ofthe masonry structure or, if the entire body of the bit has entered thehole,

to the zone around the shank l2. The groove 22,-

at its points of intersection with the thread I'I, provides additionalsharp edges by which any large particles that may have travelled to the4 outer end of the bore I l before emerging through the slot 2|-as forexample when the hole being drilled is directed or inclined upwardlymaybe further comminuted. Thus the drill will free the hole of all loosematerial, of eitherchip or granular size.

Manifestly, a bit constructed in accordance with my invention providesone exterior passage means for conveying the material cut by the teethto a point exteriorly of the hole, which comprises the auger I1, and aninterior passage means for conveying the material cut likewise to apoint exteriorly of the hole, which comprises the bore or recess I I andthe slot 2|. These two means coact one with the other to constantlyrelieve the teeth of the cuttings; to reduce the cuttings to sizes whichcan freely pass out of the groove IIa, or out of the interior of the bitthrough the slot 2|; and to utilize the rotary motion of the bit toimpel the cuttings into both the groove Na and the slot 2|, and thuscause the cuttings to emerge from the hole from points interiorly and'exteriorly of the bit simultaneously. Thus the bit operates toestablish and maintain a constant flow of the loose material out of thehole to reduce [its] resistance to rotation [of the bit,] and to[thereby] increase the speed with which a hole may .be drilled [by thebit].

Although I have herein shown and described only one form of drill bitembodying my invention, it is to be understood that various changes andmodifications may be made therein without departing from the spirit ofmy invention and the spirit and scope of the appended claims.

I claim:

1. A rotary bit for drilling concrete, including: an elongate,cylindrical body having an axial bore and formed at the trailing endwith means for connection with a rotatin tool; said body being enlargedat the leading end thereof to form an annular head of greater diameterthan said body. said head being provided in the face thereof with teethdisposed on a plurality of equally angularly spaced radii, the bodybeing provided on the outer surface thereof with a spiral thread formingan auger and with a single slot extending transversely through saidthread, said slot commencing at a point adjacent the leading end of andextending longitudinally of and terminating at a point spaced from thetrailing end of the body, said slot establishing communication betweensaid bore and the exterior of said'body and said slot providing alateral outlet for the material released within the area defined by saidteeth during rotation thereof.

7 2. A rotary bit for drilling concrete, including: an elongate,cylindrical body having an axial bore and formed at the trailing endwith means for connection with a-rotating tool; said body. beingenlarged at the leading end thereof to form an annular head of greaterdiameter than saidbo'dy,"

said head being provided in the face thereof with teeth disposed on aplurality of equally angularly spaced radii and having their outerendsprojecting outwardly from the periphery of the head and their innerends projecting into the bore of said body, the body being provided onthe outer slot meaning a la eral outlet tenths mate ial rel i hin the ara d f ned y "sa eeth (131F115 Q aii ihsrsq 3- i l-ro ar it ior dri lingmmie inclu in a el ga e s sii i a lr b re y indr ca bo levies tim i n ad t eo a. r m vab e l emsa s s mi isinse too f r ta in a bdr; sail-havin e la d hea a ror removal from the hole; and said body havinga'long'itudinal linear slot extending between the.

'leadin'g'endand trailing end and communicating with the exterior ofsaid body-for conveying detrital material lnteriorly along and laterallyoutward of said body toa point beyond the material being drilled.

4. A rotary bit for drilling concrete, including:

an elongate,cylindrical body having an axial boie and'formed at thetrailing end with means for connection with a rotating tool; said bodybeing provided in the face of the leading end thereof with teethdisposed on a plurality of angularly spaced radii and having their outerends projecting outwardly from the periphery of the body and their innerends projecting into the bore of said body, the body being provided onthe outer surface thereof with a spiral thread forming an auger and witha single slot extending transversely through said thread andlongitudinally of the body and establishing communication between saidbore and the exterior of said body, said slot providing a lateral outletfor the material released within the area defined by said teeth duringrotation thereof.

5. A rotary bit for drilling concrete, including: an elongate,cylindrical body having an axial bore and formed at the trailing endwith means for connection with a rotating tool; said body being providedin the face of the leading end thereof with teeth disposed on aplurality of equally angularly spaced radii and having their outer endsprojecting outwardly from the periphery of the body and their inner endsprojecting into the bore of said body, the body being provided on theouter surface thereof with a spiral thread forming an auger and with asingle slot extending transversely through said thread, said slotcommencing at a point adjacent the leading end of and extendinglongitudinally of and terminating at a point spaced from the trailingend of the body, said slot establishing communication between said boreand the exterior of said body, and said slot providing a lateral outletfor the material released within the area defined by said teeth duringrotation thereof.

6. A rotary bit for drilling concrete and the like including anelongated cylindrical body provided interiorly with a bore extending itsfull length and formed exteriorly with a spiral thread, arouately spacedteeth extending substantially radially in one end face of said body, theends of said teeth projecting radially slightly beyond the thread onsaid body and also extending radially s i htly ete said 12 s a. el nated sl mans l iw iudi ial u .ofaid bod inter thre and ponnss nas l heew ofs dbcd qnde' ank ela li h wdvf i y imedefr 1 F i 7. A' rotarybit-for drilling concrete and the ik in l a n ate e l aii sel b9 114 a na head en an are and s by tsn riiw n d' w said wil br ins I d ie i i/ eaer s n s ith? r ml'th whi hen" its d n ar s s id ha e wasperpendicularly 'to 'tjheiloiigitudinal axis ojfsaid some"? b -i" in anyn i dinal-1 h r urpo tino s elf, a jcuately .sme i extending su s i ly aia ice sir-me or a odfl! h w s mil t h ma sin radially slightly beyondthe thread on'f said body and also extending radially slightly into saidbore, n el n 1? m nd lon tud nal y Q said body intersecting said threadand connecting said bor with the exterior of said body, anda shankextending rigidly from the end of said body spaced from said teeth.

A rotary bit for drilling concrete and the like including an elon atedcylindrical body It inga head'end and as'paced shank end, ri dabrasion-resistant teeth at the head end of said body extending radiallyslightly beyond said body ,for the purpose, said body being rotated, ofcutting a hole into which said body can ep-f' tend, said body includingmeans to feed particles from said head and toward said shanh end ,Qmprising a longitudinal bore extended through said body, a spiral threadencircling said body the conooluiions of said thread forming a groove,and a linear slot in the wall of said body through which particles canpass connecting said bore to the groove spacing the convolutions of saidthread, and a shank extended longitudinally from the shank end of saidbody adapted to receive a rotating force.

9. A rotary hit for drilling concrete and the like including a rotatablecylindrical body having a forward end and a trailing end and formed witha longitudinal bore, a plurality of cutting elements fixedly carried bythe forward end of said body and extended radially inwardly andoutwardly therein for the purpose of cutting a channel in a contactedmaterial as said body rotates in contact therewith under pressure andinto which channel said body can advance as said channel deepens, theinward radial extensions of said cut ting elements being adapted tooomminute a core formed in said material inside said channel, a Zen.gitudinal slot in said body opening into said bore and through whichpieces of said core can be thrown centrifugally, and a multiplicity ofcutting edges positioned along said slot formed by the intersectiontherewith of a spiral thread encircling said body, said cutting edgesbeing adapted further to oomminuie pieces of material thrown throughsaid slot from said bore.

10. A rotary bit for drilling concrete and the like including anelongated cylindrical body provided interiorly with a bore extending itsfull length and formed erteriorly with a spiral thread, arcuately spacedteeth extending substantially radially in one end face of said body andformed individually at their cutting ends with sloping, forwardlyconverging, inner and outer corner portions radially spaced by a centralportion lying in a plane substantially normal to rotational axis of saidbody, the radially spaced ends of said teeth projecting radiallyslightly beyond the thread on said body and also extending radiallyslightly into said bore, an elongated slot extended longitudinally ofsaid body intersecting said thread and connecting said bore with theexterior of said body, and a shank extending rigidly from the end ofsaid body spaced from said teeth.

11. A rotary bit ,for drilling concrete and the like including anelongated cylindrical body provided interiorly with a bore extending itsfull length and formed exteriorly with a spiral thread, arcuately spacedteeth extending substantially radially in one end face of said body, theends of said teeth projecting radially slightly beyond the thread onsaid body and also extending radially slightly into said bore, anelongated slot extended longitudinally of said body intersecting saidthread and connecting said bore with the interior of said body, a groovein the exterior of said body intersecting said thread and forming acontinuation of said slot, and a shank exteniding rigidly from the endof said body spaced from said teeth. 12. A rotary bit for drillingconcrete and the like including an elongated cylindrical body haping ahead end and .a spaced shank end, rigid abrasion-resistant teeth at thehead end of said body extending radially for the purpose of cutting ahole into which said body can advance upon said body being rotated aboutits longitudinal axis, said body including means to feed materialdisplaced by said teeth from said head end toward said shank endcomprising a longitudinal bore in said body, a spiral thread encirclingsaid body the con'volntions of said thread forming a groove, and

an opening in said body intersecting at least one turn of said threadand having anarea of'the magnitude of the cross-sectional area of saidbore, said opening providing'a discharge for material from the interiorof said body to the exterior thereof where said material can bedisplaced by said thread in the rotation of said drill, and a shankextended longitudinally from the shank end of said body adapted toreceive a rotating force.

1 CARL V. TILDEN.

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